The Great South Wall stretches 7 km from O’Connell Bridge to Poolbeg lighthouse, and is reputedly Europe’s longest sea wall. The final 2km walk out into the sea is bracing, and a good place to inspect the construction. Built in 1748-1790, the wall is a key part of Dublin port and docks.

This Victorian diving bell on Sir John Rogerson’s Quay (pictured) was crucial in redeveloping the quays in the late 1800s. Devised by Irish engineer Bindon Blood Stoney, it allowed labourers to work underwater with his innovative technique of using massive pre-cast concrete blocks in place of rubble walls.